Kriish Tyagi stunned second seed Hamish Stewart 7-6(7), 5-7, 6-4, to scalp the biggest win of his fledgling career, and advance to the semifinals of the Karnataka Open ATP Challenger at the S.M. Krishna Tennis Stadium here on Thursday.

The 19-year-old saved three break points in the ninth game to force a tie-breaker in the first set before winning it. Stewart (World No. 328) won the second before Tyagi broke serve to take a 5-4 lead in the decider. The World No. 1332 soon sealed the encounter which lasted two hours and 40 minutes.

Tyagi did well to counter Stewart’s big serves. “I have played big servers before and learnt that if I can make two good returns, they suddenly don’t know what to do. I just tried to stay solid and keep putting the ball back in play,” Tyagi said on countering Stewart’s big serves.

Tyagi will face fourth seed Philip Sekulic of Australia in the last-four on Friday.

Fellow Indian Manish Sureshkumar went down 3-6, 3-6 to former World No. 40 Ilya Ivashka, while American Keegan Smith got the better of the Serb Ognjen Milic 7-6(5), 6-3.

The results (quarterfinals): Ilya Ivashka bt Manish Sureshkumar 6-3, 6-3; Keegan Smith (USA) bt Ognjen Milic (Srb) 7-6(5), 6-3; Philip Sekulic (Aus) bt Maximus Jones (Tha) 6-7(6), 6-3, 6-1; Kriish Tyagi bt Hamish Stewart (GBr) 7-6(7), 5-7, 6-4.

Doubles: Petr Bar Biryukov & Grigoriy Lomakin (Kaz) bt Sergey Betov & Jeevan Nedunchezhiyan 4-6, 7-5, [10-8]; Prajwal Dev & Nitin Kumar Sinha bt Jeffrey Chuan (Tpe) & Christopher Papa (USA) 6-4, 7-5; Niki Poonacha & Saketh Myneni bt Sidharth Rawat & Manish Sureshkumar 6-3, 7-6(3); Adil Kalyanpur & Mukund Sasikumar bt Dominik Palan (Cze) & Digvijaypratap Singh 7-6(5), 6-3.